ShackDeck
Sign in Download Free Now

What to listen to · Fax and digital signals

NCDXF beacons on 14.100 MHz: eighteen stations that show where 20 metres is open

Eighteen beacons around the world take turns on 14.100 MHz, each sending its callsign and four dashes at falling power in a ten-second slot. With a receiver and a clock you can tell where 20 metres is open.

Frequency14100 kHz
ModeCW

What you hear

Every ten seconds a new voice in Morse: a callsign at 22 words per minute, then four dashes of one second each. The dashes are the point. The callsign and the first dash go out at 100 watts, the second dash at 10 watts, the third at 1 watt, the fourth at 100 milliwatts, so each beacon measures the path for you on the spot. On the waterfall the four dashes form a staircase stepping down into the noise, and how many steps you can see is the answer: all four means the path is wide open, one means it is barely there. After eighteen slots, three minutes, the cycle repeats.

Which beacon is which you tell by the clock. The cycle starts on the minute divisible by three, at 00:00 UTC and every three minutes after, with 4U1UN at the United Nations in New York, followed in turn by VE8AT in the Canadian Arctic, W6WX in California, KH6RS in Hawaii, ZL6B in New Zealand, VK6RBP in Western Australia, JA2IGY in Japan, RR9O in Novosibirsk, VR2B in Hong Kong, 4S7B in Sri Lanka, ZS6DN in South Africa, 5Z4B in Kenya, 4X6TU in Israel, OH2B in Finland, CS3B on Madeira, LU4AA in Argentina, OA4B in Peru and YV5B in Venezuela. Each beacon then moves up to 18.110, 21.150, 24.930 and 28.200 MHz in the following slots, so the same callsign is heard on five bands within fifty seconds.

Who transmits and why

The Northern California DX Foundation built the network together with the International Amateur Radio Union, starting in 1979, and amateur radio clubs host the beacons around the world. The purpose is a calibrated, real-time look at propagation that any listener can make with nothing but a receiver and a watch, and that automatic monitoring stations use day and night. Not all eighteen are always on the air; a beacon can be off for months for repairs, and the foundation publishes which ones are working, so a missing slot is not necessarily a closed path.

When and where to listen

Any hour, as the cycle never stops; what changes is who gets through. From Europe in daylight OH2B, CS3B and 4X6TU are usually loud; in the afternoon W6WX, VE8AT and 4U1UN come in from the west; towards the evening LU4AA and YV5B from the south-west; in the morning JA2IGY, VR2B and RR9O from the east. Near the peak of the solar cycle a full cycle can bring in a dozen beacons; near the minimum you may hear four. The slots are timed to the second, so a clock on UTC is essential, and the band should be reasonably quiet: 14.100 sits at the top edge of the digital segment, and a nearby RTTY station can mask the weaker dashes.

In ShackDeck

Station catalogue → Fax and digital signals → NCDXF beacons 20 m (14.100). The program picks a public receiver with 20 metres, tunes it to 14.100 MHz and sets the CW mode with a narrow filter; no receiver, antenna or account of your own is needed. The UTC clock in the program's header tells you which slot is running, the callsign is short enough to read by ear even at 22 words per minute, and the staircase of the four dashes is visible on the waterfall before you hear it. The receiver-stepping buttons next to the receiver's name move to the next public receiver that has the frequency, so the same three-minute cycle can be compared from several continents in a row.

More stations

APRS on 144.800 MHz in Europe: cars, weather stations and digipeaters on the map

144.800 MHz · APRS

On 144.800 MHz European amateur stations send short packets with their position, weather and messages: cars on the move, home weather stations, digipeaters on hills. ShackDeck decodes them and puts everything on the map.

SSTV on 20 metres, 14.230 MHz: pictures sent as sound

14230 kHz · SSTV

On 14.230 MHz amateurs send photographs and greeting cards as a two-minute warble, line by line. ShackDeck recognises the mode from the header and assembles the picture on screen as it comes in.

APRS on 144.390 MHz: the North American frequency

144.390 MHz · APRS

The same packet network as on 144.800 MHz in Europe, on the frequency used across the United States and Canada. ShackDeck takes a receiver in the USA and puts the cars, weather stations and digipeaters on the map.

Amateur RTTY on 20 metres, 14.083 MHz: 45.45 baud teletype and weekend contests

14083 kHz · RTTY

Radio amateurs still run the teleprinter of the 1930s over the air: two tones 170 Hz apart at 45.45 baud, between 14.080 and 14.090 MHz. ShackDeck prints the text; on contest weekends the band is full of it.

QO-100: SSB contacts through the geostationary satellite on 10489.700 MHz

10489.700 MHz · USB

The only amateur transponder in geostationary orbit hangs over Africa and never sets. On 10489.700 MHz its SSB segment carries voices from Brazil to Thailand around the clock, heard through public receivers with a dish.

ISS on 121.750 MHz: Orlan spacesuits and Soyuz on AM

121.750 MHz · AM

During Russian spacewalks, and when a Soyuz or a Progress approaches the station, the suit radios and the ship's voice channel come up on 121.750 MHz in AM. Silent most of the year, then a few hours of rare voices.